Container inspection system is essentially composed by a radiation source generating X-ray of high energy and detector arrays receiving the X-rays penetrating the container. The density distribution of the objects contained in the container is exhibited and obtained by the intensity variation of the X-ray penetrating through the container into the detectors, with the X-ray intensity being converted into grey level of an image, when the container passes the X-ray beams. Conventionally, the container inspection system is divided into a fixed container inspection system, a built-on vehicle movable container inspection system and a combined mobile container inspection system etc. The fixed container inspection system can achieve stable image quality whereas it occupies large area, and the construction cost a lot with a long period, and once built, it must be fixedly used. The built-on vehicle movable container inspection system is typically a vehicle on which all the scanning, detecting and controlling devices are carried, or two vehicle of which one is installed with the scanning and detecting devices, the other with the controlling device to separate human from harmful radiation source, but the detection range is confined due to the vehicle configuration, and the devices adjustment is difficult.
Chinese Patent CN2410260A discloses a “detachable combined mobile container detection device”, which adopts a superposition combined structure and dissembles the whole device into detachable parts based upon modular design concept. The device can be transferred from on inspection site to another. It can overcome most disadvantages of the fixed container inspection system mentioned above with stable structure, shortened manufacturing period, reduced construction costs and less area occupation. It also increases the scanning/detecting range, ameliorates the working conditions of the scanning/detecting devices and enhances the reliability and image quality of the device compared with the built-on vehicle movable container inspection system. The inspection device, however, can not inspect the chassis of the vehicle, and is restricted when a vehicle with special height or parking deviation has dead angle. Moreover, site transferring lasts a long time, for example, about four weeks.
Chinese Patent CN2572400A discloses a “built-on movable vehicle container inspection system”, which reduces the intensity of the radiation source which is installed under a rotatable deck, and ensures that the vehicle chassis and partial tires can be detected with appropriate adjustment of radiation source angle, increasing scanning range. However, since vehicle chassis is still being used in the system, the device installation adjustment is difficult due to the vehicle structure confinements.